Add log when we are trying to dismiss keyguard

Such that we can blame the app!

Test: call requestDismissKeyguard, inspect logs
Bug: 63745706
Change-Id: Ie257db2276839ba3491ee1b3cb642486331544c1
Merged-In: Ie257db2276839ba3491ee1b3cb642486331544c1

services/core/java/com/android/server/am/KeyguardController.java

@@ -144,6 +144,7 @@ class KeyguardController {
             failCallback(callback);
             return;
         }
+        Slog.i(TAG, "Activity requesting to dismiss Keyguard: " + activityRecord);
         mWindowManager.dismissKeyguard(callback);
     }